Optimer Pharmaceuticals Inc. (OPTR), the antibiotics maker that’s weighing a sale, drew interest from drugmakers including GlaxoSmithKline Plc (GSK) and Japan’s Astellas Pharma Inc. (4503), said two people familiar with the matter. The shares surged. The maker of the antibiotic Dificid aims to fetch as much as $1 billion in a possible auction, said the people, who asked not to be named because the process is private. Optimer also attracted interest from Cubist Pharmaceuticals Inc. (CBST) and AstraZeneca Plc, said one of the people. Buying Optimer would allow the drugmakers to generate more revenue from hospitals, as Dificid, the company’s sole drug on the market, treats a bacterium linked to intestinal infections in hospitalized patients. The drugmaker also may prove attractive to peers that already distribute to medical facilities, because they could use existing distribution channels to reduce costs.